|Rank|Diver|Preliminary Points|Preliminary Rank|Final Points|Final Rank|Final Total|
|---|---|---|---|---|---|---|
||Ingrid Krämer (EUA)|56.30|1|34.98|2|91.28|
||Paula Jean Myers-Pope (USA)|54.70|2|35.24|1|89.94|
||Ninel Krutova (URS)|53.38|3|33.61|3|86.99|
|4|Juno Stover-Irwin (USA)|51.90|6|31.69|4|83.59|
|5|Raisa Gorokhovskaya (URS)|51.53|8|31.50|5|83.03|
|6|Norma Thomas (GBR)|51.77|7|30.44|7|82.21|
|7|Nicolle Darrigrand-Pellissard (FRA)|49.68|12|31.50|5|81.18|
|8|Phyllis Long (GBR)|52.12|5|28.86|9|80.98|
|9|Irene MacDonald (CAN)|51.31|9|29.18|8|80.49|
|10|Kumiko Watanabe (JPN)|51.04|10|28.56|10|79.60|
|11|Kanoko Tsutani-Mabuchi (JPN)|49.76|11|28.14|11|77.90|
|12|Birte Christoffersen-Hanson (SWE)|53.03|4|24.40|12|77.43|
|13|Maria Teresa Adames (MEX)|49.54|13||||
|14|Hanna Laursen (DEN)|48.89|14||||
|15|Gabriele Schöpe (EUA)|48.81|15||||
|16|Bende Velin (DEN)|48.35|16||||
|17|Laura Conter (ITA)|45.55|17||||
|18|Susan Knight (AUS)|43.03|18||||

Question: how many drivers raced in the preliminary round?
Answer: 18